Histological and immunohistochemical study of cardiac telocytes in a rat model of isoproterenol-induced myocardial infarction with a reference to the effect of grape seed extract

Zinc's protective role against hydroxychloroquine-induced cardiac effects in adult male albino rats

Background

Long exposure to Hydroxychloroquine (HCQ) has been complicated by some dangerous though infrequent cardiotoxicity.

Methods

A total of 40 normal adult male albino rats dispersed into 4 groups were used. Group 1 (Control group), Group II (HCQ treated group), Group III (zinc [Zn]-treated group), and Group IV (HCQ and Zn treated group). Once the experimentation ended, rats were sacrificed and cardiac soft tissue sections were processed twenty-four hours at the end of the experiment for histological study.

Results

Cardiac-stained sections revealed that HCQ induced widespread necrosis, dilatation, and vacuolar degeneration. However, the combination of HCQ with Zn ameliorated these damaging effects. Cardiac enzyme parameters were also studied in the 4 groups and revealed CK-MB and troponin were considerably elevated in groups II associated to the control group.

Conclusion

It was concluded that Zn revealed a protective role against HCQ cardiomyopathy in adult male albino rats. This might signify an appreciated means for Zn-based treatment in the upcoming subsequent clinical records to adjust doses and guarantee patient safeguard.

Histological study of the role of CD34+ stem cells and mast cells in cyclophosphamide-induced thymic injury in rats and the possible attenuating role of melatonin

Cyclophosphamide (CP) is an anticancer drug that adversely affects immunity and thymus structure. Melatonin is a hormone secreted by the pineal gland. It boosts immunity and has antioxidant properties. Therefore, the present study was conducted to investigate the possible protective effect of melatonin on CP-induced changes in the rat thymus. Forty male albino rats were used and divided equally into four main groups. Group I was the control group. Group II (melatonin group) received melatonin at a dose of 10 mg/kg body weight/day by intraperitoneal injection throughout the experimental period. Group III (CP group) received 200 mg/kg body weight CP by a single intraperitoneal injection. Group IV (CP + melatonin group) received melatonin intraperitoneally at a dose of 10 mg/kg body weight/day starting 5 days prior to CP injection until the end of the experiment. All rats were euthanized 7 days after CP injection. Administration of CP in group III resulted in depletion of the cortical thymoblasts. In addition, CD34-immunopositive stained stem cells decreased and mast cell infiltration increased. Electron microscopy showed degeneration of thymoblasts and vacuolization of epithelial reticular cells. Administration of melatonin with CP in group IV showed considerable protection of thymic histology. In conclusion, melatonin may protect against CP-induced thymic injury.

Cardiac Telocytes 16 Years on-What Have We Learned So Far, and How Close Are We to Routine Application of the Knowledge in Cardiovascular Regenerative Medicine?

The regeneration of a diseased heart is one of the principal challenges of modern cardiovascular medicine. There has been ongoing research on stem-cell-based therapeutic approaches. A cell population called telocytes (TCs) described only 16 years ago largely contributed to the research area of cardiovascular regeneration. TCs are cells with small bodies and extremely long cytoplasmic projections called telopodes, described in all layers of the heart wall. Their functions include cell-to-cell signaling, stem-cell nursing, mechanical support, and immunoregulation, to name but a few. The functional derangement or quantitative loss of TCs has been implicated in the pathogenesis of myocardial infarction, heart failure, arrhythmias, and many other conditions. The exact pathomechanisms are still unknown, but the loss of regulative, integrative, and nursing functions of TCs may provide important clues. Therefore, a viable avenue in the future modern management of these conditions is TC-based cell therapy. TCs have been previously transplanted into a mouse model of myocardial infarction with promising results. Tandem transplantation with stem cells may provide additional benefit; however, many underresearched areas need to be addressed in future research before routine application of TC-based cell therapy in human subjects. These include the standardization of protocols for isolation, cultivation, and transplantation, quantitative optimization of TC transplants, cost-effectivity analysis, and many others.

Effects of pinealectomy and crocin treatment on rats with isoproterenol-induced myocardial infarction

The present study aimed to analyze the effects of pinealectomy and crocin treatment in isoproterenol-induced myocardial damage. Seventy rats were divided into seven groups: control, sham control, pinealectomy (PNX), isoproterenol (ISO; 85 mg/kg on the 29th and 30th days of the experiment, subcutaneous injection), PNX + ISO, PNX + crocin (50 mg/kg/day for 30 days, intragastric administration), and PNX + ISO + crocin. PNX procedure was performed on the first day of the study. A significant increase was observed in serum cardiac damage markers (CK-MB, Troponin I) after ISO administration. ISO administration led to a significant increase in cardiac oxidative stress parameters, such as malondialdehyde (MDA) and total oxidant status (TOS), while it led to a decrease in antioxidant defense system parameters, such as reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and total antioxidant status (TAS) when compared to control groups. Elevated MDA and TOS levels were observed, while reduced SOD and CAT activities, and decreased GSH and TAS levels were observed in the group that underwent PNX and ISO administration when compared to the PNX group. Furthermore, in the PNX + ISO + Crocin group, SOD and CAT activities, and GSH and TAS levels ameliorated and MDA and TOS levels were reduced with the crocin treatment when compared to the PNX + ISO group. Also, marked increases were observed in serum cardiac markers, histopathological and immunohistochemical findings after the crocin treatment. All findings demonstrated that crocin could be employed as a cardioprotective agent due to its antioxidant, anti-inflammatory, and anti-apoptotic properties.

Morpho-functional changes of cardiac telocytes in isolated atrial amyloidosis in patients with atrial fibrillation

Telocytes are interstitial cells with long, thin processes by which they contact each other and form a network in the interstitium. Myocardial remodeling of adult patients with different forms of atrial fibrillation (AF) occurs with an increase in fibrosis, age-related isolated atrial amyloidosis (IAA), cardiomyocyte hypertrophy and myolysis. This study aimed to determine the ultrastructural and immunohistochemical features of cardiac telocytes in patients with AF and AF + IAA. IAA associated with accumulation of atrial natriuretic factor was detected in 4.3-25% biopsies of left (LAA) and 21.7-41.7% of right (RAA) atrial appendage myocardium. Telocytes were identified at ultrastructural level more often in AF + IAA, than in AF group and correlated with AF duration and mitral valve regurgitation. Telocytes had ultrastructural signs of synthetic, proliferative, and phagocytic activity. Telocytes corresponded to CD117+, vimentin+, CD34+, CD44+, CD68+, CD16+, S100-, CD105- immunophenotype. No significant differences in telocytes morphology and immunophenotype were found in patients with various forms of AF. CD68-positive cells were detected more often in AF + IAA than AF group. We assume that in aged AF + IAA patients remodeling of atrial myocardium provoked transformation of telocytes into "transitional forms" combining the morphological and immunohistochemical features with signs of fibroblast-, histiocyte- and endotheliocyte-like cells.

Telocytes in the hearts of Saanen goats

Telocytes, new interstitial cells that have received significant attention in recent years, have been detected in many organs, including the heart. The distinction between telocytes and other interstitial cells can only be made based on their ultrastructural characterization and immunophenotypic features. In this study, we examined the interstitial cells in the healthy heart tissues of Saanen goats to determine whether they are telocytes or not, by using a scanning electron microscope (SEM) and immunohistochemical and immunofluorescence staining methods. The SEM revealed oval and round telocytes with two to four telopodes. Some telopodes also had podoms. The staining for immunohistochemical and immunofluorescence methods used for CD34, c-kit (CD117), and vimentin antibodies. Positive cells were detected in the heart muscle and heart valves by immunohistochemical staining. As these antigens can also be expressed by other non-telocyte cells, we used double immunofluorescence staining with CD34/c-kit and CD34/vimentin antibodies to identify true telocytes. Telocytes were determined in the right atrium and aortic valve. While telocytes were CD34+/c-kit+ and CD34+/vimentin+, fibroblasts were CD34-/vimentin+. These results confirm the presence of telocytes in the hearts of Saanen goats.

Telocytes and lymphatic endothelial cells: Two immunophenotypically distinct and spatially close cell entities

Telocytes (TCs) have recently emerged as a peculiar type of stromal cells located in both perivascular and interstitial compartments of multiple anatomical sites in humans, other mammals and vertebrates. Pioneer electron microscopy studies have ultrastructurally defined TCs as "stromal cells with telopodes" (i.e. very long and thin cell processes with a moniliform morphology conferred by the irregular alternation of slender segments and small, bead-like, dilated portions), whereupon it has become apparent that TCs largely correspond to the CD34+ stromal/interstitial cells detectable by immunohistochemical assays. Besides CD34, TCs are also characterized by the expression of platelet-derived growth factor receptor (PDGFR)α. Interestingly, recent works recommended that lymphatic endothelial cell (LEC) markers should be routinely assessed to discriminate with certainty TCs from LECs, because these two cell types may exhibit similar morphological traits, especially when initial lymphatics are sectioned longitudinally and appear as vascular profiles with no obvious lumen. Furthermore, it has been argued that lymphatic microvessels immunostained for the small mucin-type transmembrane glycoprotein podoplanin (PDPN), which is widely used as lymphatic endothelial marker, can be easily misidentified as TCs. Nevertheless, surprisingly these assumptions were not based on double tissue immunostaining for TC and LEC markers. Therefore, the present morphological study was undertaken to precisely investigate the mutual spatial organization and putative relationships of TCs and lymphatic vessels in tissues from different human organs. For this purpose, we carried out a series of double immunofluorescence analyses simultaneously detecting the CD34 or PDGFRα antigen and a marker of LECs, either PDPN or lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1). In the connective tissue compartment of different organs, TCs were CD34+/PDGFRα+/PDPN-/LYVE-1- while LECs were CD34-/PDGFRα-/PDPN+/LYVE-1+, thus representing two definitely distinct, though spatially close, cell entities. The arrangement of telopodes to intimately surround the abluminal side of LECs suggests a possible role of TCs in the regulation of lymphatic capillary functionality, which is worth investigating further.

d-Limonene Ameliorates Myocardial Infarction Injury by Reducing Reactive Oxygen Species and Cell Apoptosis in a Murine Model

Myocardial infarction (MI) leads to high mortality, and pharmacological or percutaneous primary interventions do not significantly inhibit ischemia/reperfusion injuries, particularly those caused by oxidative stress. Recently, research groups have evaluated several naturally occurring antioxidant compounds for possible use as therapeutic alternatives to traditional treatments. Studies have demonstrated that d-limonene (DL), a monoterpene of citrus fruits, possesses antioxidant and cardiovascular properties. Thus, this work sought to elucidate the mechanisms of protection of DL in an isoproterenol-induced murine MI model. It was observed that DL (10 μmol) attenuated 40% of the ST elevation, reduced the infarct area, prevented histological alterations, abolished completely oxidative stress damage, restored superoxide dismutase activity, and suppressed pro-apoptotic enzymes. In conclusion, the present study demonstrated that DL produces cardioprotective effects from isoproterenol-induced myocardial infarction in Swiss mice through suppression of apoptosis.

Comparative Study of the Therapeutic Potential of Mesenchymal Stem Cells Derived from Adipose Tissue and Bone Marrow on Acute Myocardial Infarction Model

OBJECTIVES

Stem cell therapy is a promising approach in the treatment of acute myocardial infarction (AMI). Mesenchymal stem cells (MSC) from bone marrow (BM-MSC) and adipose tissue (AT-MSC) are attractive and feasible for preclinical and clinical trials. In this study, we compared the therapeutic potential of BM-MSC and AT-MSC in repairing the hearts of rats with isoproterenol (ISO)-induced AMI.

METHODS

Forty-two female rats were assigned into two groups; the optimization and the experimental group. The optimization groups were further subdivided into control group and the AMI induced group (using ISO). The experimental group was subdivided into AMI+cell-free media injected in the tail vein, AMI+BM-MSC, and AMI+AT-MSC groups treated with the intravenous injection of their respective cell types. Twenty-eight days after induction, electrocardiogram (ECG) was performed, and heart tissue samples were collected for histological assessment and cells tracing.

RESULTS

MSC therapy repaired cardiac functions shown by the restoration of ST segment, QT and QRS intervals in the ECG when compared to the AMI group. Infarct area was significantly decreased, and cardiac tissue regeneration signs were shown on histopathological examination.

CONCLUSIONS

Both MSC sources proved to be equally efficient in the assessed parameters.

Myocardial Telocyte-Like Cells: A Review Including New Evidence

Telocytes (TCs) are a controversial cell type characterized by the presence of a particular kind of prolongations, known as telopodes, which are long, thin, and moniliform. A number of attempts has been made to establish the molecular phenotype of cardiac TCs (i.e., expression of c-kit, CD34, vimentin, PDGRFα, PDGRFβ, etc.). We designed an immunohistochemical study involving cardiac tissue samples obtained from 10 cadavers with the aim of determining whether there are TC-like interstitial cells that populate the interstitial space other than the mural microvascular cells. We applied the markers for CD31, CD34, PDGRFα, CD117/c-kit, and α-smooth muscle actin (α-SMA). We found that, in relation to two-dimensional cuts, the endothelial tubes could be misidentified as TC-like cells, the difference being the positive identification of endothelial lumina. Moreover, we found that cardiac pericytes express PDGRFα, CD117/c-kit, and α-SMA, and that they could also be misidentified as TCs when using light microscopy. We reviewed the respective values of the previously identified markers for achieving a clear-cut identification of cardiac TCs, highlighting the critical lack of specificity.

Food Bioactive HDAC Inhibitors in the Epigenetic Regulation of Heart Failure

Approximately 5.7 million U.S. adults have been diagnosed with heart failure (HF). More concerning is that one in nine U.S. deaths included HF as a contributing cause. Current HF drugs (e.g., β-blockers, ACEi) target intracellular signaling cascades downstream of cell surface receptors to prevent cardiac pump dysfunction. However, these drugs fail to target other redundant intracellular signaling pathways and, therefore, limit drug efficacy. As such, it has been postulated that compounds designed to target shared downstream mediators of these signaling pathways would be more efficacious for the treatment of HF. Histone deacetylation has been linked as a key pathogenetic element for the development of HF. Lysine residues undergo diverse and reversible post-translational modifications that include acetylation and have historically been studied as epigenetic modifiers of histone tails within chromatin that provide an important mechanism for regulating gene expression. Of recent, bioactive compounds within our diet have been linked to the regulation of gene expression, in part, through regulation of the epi-genome. It has been reported that food bioactives regulate histone acetylation via direct regulation of writer (histone acetyl transferases, HATs) and eraser (histone deacetylases, HDACs) proteins. Therefore, bioactive food compounds offer unique therapeutic strategies as epigenetic modifiers of heart failure. This review will highlight food bio-actives as modifiers of histone deacetylase activity in the heart.

Cardiac telocytes. From basic science to cardiac diseases. II. Acute myocardial infarction

INTRODUCTION

The purpose of this study was to evaluate the scientific evidence regarding a potential role of telocytes in myocardial infarction.

MATERIALS AND METHODS

To this purpose, we performed a systematic review of relevant scientific literature, indexed in PubMed, Web of Science, and Scopus.

RESULTS AND DISCUSSIONS

We found six articles containing relevant studies aimed at liking myocardial infarction and telocytes. The studies that were analysed in this review failed to show, beyond a reasonable doubt, that telocytes do actually have significant roles in myocardial regeneration after myocardial infarction. The main issues to be addressed in future studies are a correct characterization of telocytes, and a differentiation from other cell types that either have similar morphologies (using electron microscopy) or similar immunophenotypes, with emphasis on endothelial progenitors, which were previously shown to have similar morphology, and functions in cardiac regeneration after myocardial infarction.